d.
Do you think that Tmust include the edge of G with
the least weight?
Yes.
What about the edge with the second-least weight?
Yes.
What about the edge with the third-least weight?
No.

Kruskal's algorithm must choose the first two edges, because
it is impossible that the endpoints of those edges are already connected by
a path.
However, the third edge is rejected if the first three edges form a triangle.

e.
Θ(n2 + e log e) =
Θ(n2 + e log n);
either expression is correct.

f.
Asymptotic notation is meaningful only as
the number of edges e approaches infinity.
In a 100-vertex undirected graph, the number of edges cannot exceed 5,050.